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Rusty leaking rear Diff


Active Member
Feb 12, 2021
Country Flag
Hi all.
Has anyone had success with using Steel Putty filler? I have a slight oil leak on the rear diff where the handbrake cable bracket is welded to it.
Garage says its not too bad but thought I would clean it off, KURUST it then cover with metal putty then paint it over. Don't really want to weld a plate over it if I can help it.
Its been used to buy time for others who never mentioned the problem again for 2 or 3 years and JBWeld now have a high heat version which might last longer again ?
I ended up welding the diff on my old 90, After many attempts, using putty and all kinds of Tiger seal.. The problem is the Steel is so impregnated with oil its difficult to get a clean surface to get anything to stick.. Grinding it back with a Flap disc (not a hard Disc) helps .. But you end up trying to Weld Tin Foil... But it is Possible..... Just another weak spot on the 90 Back axle im afraid
When its like that its "wack a mole" time. If you love your Collie its new case time, if not then its goodbye time.
To stop it leaking initially I'd clean the area with brake cleaner and seal with silicone RTV for a temporary repair.
I had a porous rear diff and sorted it for a while with JB Weld. I did document it here somewhere...Had to keep applying it because I didn't make a proper (if you can ever call it that) the first time.

Drain the diff oil and clean the whole back of the diff with a wire brush or disk. Then wash with degreaser/brake cleaner several times and let it dry completely. Then apply the JBweld - I rolled it out into a pancake and just pressed it onto the diff.

In hindsight, I'd apply the putty to a much larger area than you first think you need.

It started seeping gently a few months ago but nothing drastic, however really need to address it properly now.

Unfortunately axle cases are not in stock since before Xmas at Milners. Not sure when they'll be back in....
Someone recently asked at Milners and had the "not in stock" answer. A week later they contacted him to say they had one. Whether that was just the 1, dont know, but worth ringing them.
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Thanks for all the replies. I cleaned it locally and applied some TEROSON. I'll just wait and see now. Not very elegant but if it holds I'll tidy it up.
If it hold for 6 months I'll be happy but as chadr mentioned I'll drain it and really get it back to the metal in a bigger area and re-apply.
Does anyone know if JBweld is better than TEROSON?
Interested in changing the axle case if you can get one, looks a massive job. Any thoughts tips on how this would be tackled?
Well, it didn't last long at all before it started seeping. So drastic measures required.
I took a leap of faith after talking to Jason at MWS in Kidderminster. He was extremely knowledgeable and reassuring.
Basically MWS cut out the affected section out of the Diff housing and welded a new piece in. Fabricated a new hand brake cable bracket and coated it all with underseal. Refilled the diff and off I go!
Basically MWS saved the truck in a way. It would only have got worse to the point of leaking out the oil and undrivable.

Cut out section. Notice the small pin hole top right of the plate and the dark area where the rust blister was:


Plate welded in:

Finished job:

MWS details
Good result. On the notion of this being a weak spot, I always try to remember that, particularly in the UK, these trucks have spent at least 20 years in a damp, cool environment, with 50% extra free added road salt every winter. I'm not surprised the underside gets into trouble.
I always planned to flush out the old oil after a 100 miles or so, I'm glad I did. The magnetic drain plug done its job!
I bought a new one so I put the old one in the fill hole so I can check again without draining the oil. That being said I'll flush it out again in a 1000 miles or so, just to make sure I got everything out.
The oil actually had a metallic shine to it. Not sure if you can see.


I can't remember exactly but the (magnetic) drain plug is deeper than the fill plug by a few mm IIRC? Just make sure it doesn't foul any internals as I don't believe there is a lot of clearance!

I'm sure it will be fine - just a thought though.
Thanks for the clarification - the rear diff fill/drain plugs are the same on the transfer case too from memory, so you'll have a few spares.